The present invention relates to a rotary type mode switch system utilized in a magnetic tape recording device such as VCR and the like, and in particular to a non-contacting rotary type mode switch system wherein a plurality of reflector pieces are formed respectively on tracks of a plurality of concentric circles on a rear surface of a mode switch gear, and a plurality of opto-reflection sensors for discriminating the presence or absence of the reflector pieces is provided on a top surface of a switch body, so that the rotating mode of a cam gear can be determined.
In the usual VCR, deck part mechanisms including a tape cassette loading device, tape loading device, tape running device, brake device, driving force cut-off device driven in accordance with various modes, and a mode variation mechanism is carried out by a cam gear having a cam groove formed at least at one surface of an upper and lower surface and gear teeth are formed at a peripheral circumference.
The cam gear is rotated by meshing with a driving gear rotated by a driving force transmitted from a driving source such as a driving motor, and the like, and the cam gear and a sliding type operating plate or operating lever are cooperatively driven so that the running mechanism is formed to operate by each mode, such as play (Play), review (Rev), normal and reverse fast winding (FF) (Rew), and stop (Stop), and the like.
In the driving systematic mechanism, the mode switch device is utilized for detecting the rotational position of the cam gear, and the rotary mode switch employed for a conventional VCR, as shown in FIGS. to 3, is structured such that a brass made contactor 2 is attached on the rear surface of a mode switch gear 1 having external teeth 1a. A similar brass made contactor band 4 is attached at the central portion of a mode switch body 3 made of plastic material, and the mode switch gear 1 is rotatably fixed around an axle pin 3' on the switch body 3 so that the rotational position of mode switch gear 1 is recognized in response to the contacting condition of contactor 2 and contactor band 4. This conventional rotary type mode switch is mounted to a deck part, and electrically connected to a control part, and when cam gear 6 is rotated around axle shaft 6' according to the rotation of driving force transmitting gear 5 by the driving force of the driving motor, a pinion 7 formed integrally thereof is rotated and the mode switch gear 1 coupled therewith is rotated around the axle pin 3', accordingly contactor 2 becomes contacted with contactor band 4. One of the contacting terminals 4a, 4b and 4c of the contactor band 4 is for a common signal line, and a signal of the operating mode becomes possible to be read out according to the contacting position of the mode arrangement of the contactor band 4 and contacting points 2a, 2b and 2c of contactor 2. Reference numeral 11 represents a connector for signal connection in the drawing.
However, since the conventional rotary type mode switch is formed to read out the signal by contacting the contactor band 4 having a plurality of contacting terminals 4a, 4b and 4c and the contactor 2 having a plurality of contacting points 2a, 2b and 2c, resistance variation caused from abrasion or danger of electric discharge and the like are involved, and contact becomes unstable in the case of a mechanical deformation so that the reliability is decreased and life time is shortened, and also there is the problem that a lubricating material is required for contacting.
Further, since in the conventional mode switch device the mode switch is separated from the cam gear, a space for mounting the mode switch is required. Accordingly there is the problem of decreasing the setting space of the mode switch device.